Knee orthoses or braces are widely used to provide support for injured and weakened knee joints. Such braces typically include upper and lower bars joined together to pivot about an axis through the knee joint with the upper bar being attached to at high engaging cast or component and the lower one being attached to a calf engaging cast or component. The brace provides support to prevent sideways motion of the knee joint and additionally serves to limit the bending motion of the knee. This limiting is done by controlling the angular travel of the upper and lower bars about the pivotal axis of the brace. In the case of injured or weakened knees that are being strengthened in a rehabilitation program, it is desirable to have a brace with an adjustable range wherein the amount of bending motion of the knee can be gradually increased as the knee joint strengthens.
One of the most widely used knee orthoses is that of U.S. Pat. No. 4,337,764 to Lerman. This brace uses a polycentric pivot and additionally provides an adjustable stop mechanism to control the travel of the pivot. The stop mechanism employs a bracket with an arcuate slot and stop pins. In Lerman's preferred embodiment, the arcuate slot extends beyond the edges of the upper bar of the brace and the stop pins are adjusted to engage opposite edges of the bar to control the angular travel of the upper bar about the pivot. As disclosed, the brace can be modified so that the stop pins engage opposite edges of the lower bar instead of the upper bar if desired. The Lerman stop pins frictionally engage the bracket adjacent the arcuate slot and can be independently and infinitely adjusted along the slot to selectively limit the forward and rearward motion of the knee. In contrast, the adjustable knee joint of the present invention is adjustable in fixed increments due to the use of serrations. In this manner, the allowed motion of the brace of the present invention can be selectively increased or decreased a desired amount (e.g., one degree) by moving the stop member a known number of serrations (e.g., three). Additionally as discussed in more detail herein, the structure of the present knee brace generates relatively small forces on the stop members thereby reducing the risk of accidental displacement or breakage of the stops.